The objective of the clinical component of this project is to derive information from studies in humans which will serve to clarify the etiology of root surface caries. Specifically, we will model the disease process in terms of associated parameters including past coronal caries experience, extant microflora, periodontal status, oral hygiene, carbohydrate consumption, salivary flow rate, fluoride exposure, fluid antibody levels, medications, age, sex, and socieconomic status. The data will be treated by multivariate methods successfully applied in previous studies. Additionally, a comparison of root caries experience and associated parameters will be made in special risk groups including diabetics, chronic antibiotic users, individuals in areas with varying levels of waterborne fluorides, and individuals who restrict the intake of refined carbohydrates. Finally, a core group of paid volunteers will be followed longitudinally to study a variety of key clinical, microbiological, chemical and immunological factors.